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Tree to 8–10 m. Bark dark grey and broken into sections, giving a rough appearance. Branches slender and pendulous. Branchlets yellowish, brown or deep reddish brown, largely glabrous, though the apices may be pubescent. Leaves largely deciduous, 4.5–9 × 1–2.5 cm, lanceolate to elliptic or obovate, largely glabrous, upper surface glossy dark green with slight sheen, lower surface glossy and with occasional tufts of tomentum in the vein axils, five to seven secondary veins on each side of the midrib, margins with eight to ten teeth or shallow lobes (rarely entire), terminating in spiny bristles (one to nine in total), apex acute to attenuate; petiole 1–2 cm long, glabrous or with a few hairs. Cupule saucer- or bowl-shaped, 0.7–1 × 0.4–0.6 cm, outer surface glabrous or with a few hairs, inner surface uniformly pubescent; scales acute and appressed, sometimes tuberculate at the base of the cupule. Acorn ovoid to ellipsoid, with one-quarter to one-third of its length enclosed in the cupule, 0.9–1.8 cm long, stylopodium prominent. Fruiting in the second year (USA). Nixon 1997, Melendrez 2000. Distribution USA: Texas (Chisos Mts.). Habitat Dry rocky canyons between 0 and 1650 m asl. USDA Hardiness Zone 6. Conservation status Critically Endangered. Quercus graciliformis suffers ongoing habitat disturbance, degradation and loss. Illustration Nixon 1997.
Quercus graciliformis is a small tree with graceful, slender, drooping branches, as its name suggests, and has a summer flush of paler leaves. Despite being confined as a native to a very limited area in Texas, it seems to flourish almost everywhere it is cultivated, although it is possibly intolerant of alkaline soils (Melendrez 2000). Sternberg (2004) considers that it is not likely to be hardy beyond Zone 8, but Melendrez (2000) indicates that it is very cold-tolerant, and a nice-looking specimen at the JC Raulston Arboretum is flourishing in Zone 7 conditions. Received as a small plant in 2000, this had reached 3 m by 2004 (JC Raulston Arboretum collection database). A specimen seen at the Hoyt Arboretum in Portland, Oregon in 2004 is also growing fast (7 m tall after six years, in 2004), but is unfortunately leaning. At the Hillier Gardens there are trees raised from acorns collected by Guy Sternberg in 1996 from plants at the Texas A&M University. The best is now 6.2 m high (2008), with a straight trunk, and seems to be growing very fast; although these specimens show some atypical characters, this may be a response to cultivation rather than evidence of hybridity (A. Coombes, pers. comm. 2007). Similar rapid growth has been reported from France, even when trees are growing on apparently inhospitable sites (Lamant 2004). At Arboretum de la Bergerette, one specimen grown from the Sternberg collection mentioned above is ‘a superbly shaped pyramidal tree’; in 2006 it had grown to ‘around 9 m tall in eight years, virtually evergreen and completely impervious to cold and drought’ (S. Haddock, pers. comm. 2006), and by 2008 it had reached 12.5 m (A. Coombes, pers. comm. 2008).